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Carbon rims and braking(6 posts)

Carbon rims and brakingoddsos
Jan 27, 2004 1:00 AM
After a season of racing on Open Pros I have saved up a bit of cash and am thinking about buying some deep rimmed carbon wheels. After reading lots of reviews I have settled on the Zipp 404 tubulars as having a most of the properties I want. However as I will be using these wheels mainly for road races I have one slight misgiving. Will the braking performance match up to my Open Pros?

All of my friends at the club talk about poor or grabby braking on carbon rims. Zipp's web site says that this is due to the carbon rim having a lower heat capacity than aluminium due to it's thermal properties and lower mass. This causes the rim to heat up more and the brake pads to become hotter, grabbing the rim. Zipp suggest that certain brands of brake pads (Zipp, Koolstop and Shimano) have a higher thermal conductivity carrying the heat away from the braking surface and so giving more consistant braking. This sounds plausible to me however I was hoping that someone on this forum might be able to confirm how well it works in practice.

The Zipp wheels also have a ceramic coated braking surface. I assume this helps wet weather braking and reduces wear. Again I'd like to hear your experiences.

Finally I will be using Open Pros to train on and swapping to the Zipps for races. Will carbon specific brake blocks work okay on aluminium (admittedly it will be a little expensive in brake pads) or will I have to change the pads each time I change wheels?

Chris
I rode 303s...biknben
Jan 27, 2004 9:07 AM
I had a pair of '01 303s. It was the first year they added the cilica/ceramic braking surface. I put approximately 4-5k miles on them. I used standard Shimano pads and Koolstop ceramic pads. The Shimano pads wore significantly faster but provided more braking power and consistancy. With the Shimano pads, I'd say braking was very similar to aluminum rims. I can't remember an instance where I had issues while braking that I thought were a result of the carbon rims. Since they were the standard pads, I didn't worry about swapping wheels
i and
pads.

The Koolstop pads did not provide as much power and sounded terrible (grinding). They wore better but I suspect they were doing damage to the rim surface.
re: Carbon rims and brakingjw25
Jan 27, 2004 9:37 AM
Well, I can't help you too much in practice. I have some Zipp 440's, don't think they have the ceramic brake track.
I use them for TT's, so there's not much braking. With Shimano pads, they do sound a little "scrapey", but brake okay. I have gotten some wheelskid, but since I'm on skinny tubies pumped to 120-130 psi, it's not unexpected.
Kool Stop black pads (I don't think the ceramic pads are recommended, but shouldn't hurt on the ceramic'ed rims) are softer than the Shimano, and gave a lighter lever feel. I haven't used them enough to comment on uneven braking or wear - it's a TT bike.
The Zipp carbon-carbon pads are supposed to be the stuff for all rims, as they aren't abrasive at all, and conduct heat better, etc. They aren't too pricey (I've seen sets of 4 on Ebay for $29), and if they make "normal" braking with carbon rims more consistent, I'm all for them. I've been in too many races where some dude on carbon wheels skids out and takes others out, or just makes the rest of the group nervous.
As an aside, have you considered the 303's for racing? They're even lighter than the 404's, and still deep enough to offer an aero advantage. Remember, you'll be in a peloton for most of the race, and that aero only comes into play in breakaways. Buy what you want, and the 404's are nice wheels, just tossing something out there.
They work fine...terzo rene
Jan 27, 2004 11:36 AM
but I would recommend using the Zipp pads on the front and Kool Stop black on the rear. The Zipps work quite a bit better in heavy braking like on steep switchback descents - glue doesn't melt like with the Kool Stops. On the rear it doesn't make much difference and the Kool Stops are half the price.

Wet weather performance is better than aluminum rims in my experience - little lag in brakes taking effect; dry is somewhat longer stopping distance but nothing unusual.

Zipp has changed their brake pad recommendations recently, but should NEVER use ceramic pads since they just destroy the braking surface in short order (as do Mavic pads that come with SSC brakes).

I have read several places that swapping from use with ceramic/aluminum rims to carbon is a bad idea since the pads pick up small ceramic particles and then act like sandpaper when switched to the carbon ones.
This is interestingjw25
Jan 28, 2004 1:06 PM
Head to American Classic's site and look at their wheel accessories.
Seems they sell the Kool-Stop carbon pads for $9 a pair. The Zipp pads are made by Kool Stop, and I'm pretty sure they're the same thing, though KS doesn't feel the need to mention their carbon-carbon composites. At $9 a wheel, they're close enough to normal KS pads, I'm getting them for peace of mind.
re: Carbon rims and brakingJimP
Jan 28, 2004 11:02 AM
I have been riding on Nimble Crosswinds for 5 years and have gone through a set of Shimano DA regular pads. I now use the Shimano pads for carbon fibre rims which provide more even braking. Don't worry about melting the glue on your tubulars with the carbon rims - they won't transmit the heat in to the tire. The fact that the carbon rim will not transmit the heat is what causes the brake pads to melt and leave rubber deposits on the carbon braking surface which in turn causes grabbing. The Shimano pads are expensive but seem to be very good.

Jim